# 某岛

… : "…アッカリ～ン . .. . " .. .
July 17, 2015

## BZOJ 1565. [NOI2009]植物大战僵尸

http://www.lydsy.com/JudgeOnline/problem.php?id=1565
https://www.byvoid.com/blog/noi-2009-pvz


const int N = 600 + 3, M = N * N * 4;

struct Network_Flow{

int D[N], hd[N], suc[M], to[M], cap[M];
int n, m, s, t;

inline void ae(int x, int y, int c){
suc[m] = hd[x], hd[x] = m, to[m] = y, cap[m++] = c,
suc[m] = hd[y], hd[y] = m, to[m] = x, cap[m++] = 0;
}

inline void aee(int x, int y, int c){
suc[m] = hd[x], hd[x] = m, to[m] = y, cap[m++] = c,
suc[m] = hd[y], hd[y] = m, to[m] = x, cap[m++] = c;
}

#define v to[i]
#define c cap[i]
#define f cap[i^1]

LL sap(){
LL z=0; static int cnt[N],cur[N],pre[N];
fill(D,D+n,n),fill(cnt,cnt+n,0);cnt[n]=n;
int u=s;cur[s]=hd[s];while (D[s]){
#define i cur[u]
if (u==t){
int d=INF;for(u=s;u!=t;u=v)checkMin(d,c);
z+=d;for(u=s;u!=t;u=v)f+=d,c-=d;u=s;
}
#undef i
int i;for(i=cur[u];i;i=suc[i]){
if(D[u]+1==D[v]&&c){cur[u]=i,cur[v]=hd[v],pre[v]=u,u=v;break;}
}
if (!i){
if (!--cnt[D[u]])break;
D[u]=1;REP_G(i,u)if(c)checkMax(D[u],D[v]);--D[u];
++cnt[D[u]];if(u==s)cur[u]=hd[u];else u=pre[u];
}
}

return z;
}

void init(int _n){
n = _n; s = 0, t = n + 1; m = 2; n = t + 1;
fill(hd, hd+n, 0);
}

} G;
#undef v
#undef c
#undef f

VI _adj[N], adj[N]; int inD[N], scr[N], h[N], q[N] = {M}, op, cz, u, v;
int r, c, s, t, n, m, ans;

inline void add_edge(int x, int y){
}

inline int id(int x, int y){
return x * c + y + 1;
}

void init(){
RD(r, c);

REP(i, r) REP(j, c){
if (j != 0) add_edge(id(i, j), id(i, j-1));
int t, x, y; RDD(scr[id(i, j)]);
Rush RD(x, y), add_edge(id(i, j), id(x, y));
}

n = r * c;

// Toposort ..

op = 0;
REP_1(i, n) if (!inD[i])
q[++op] = i;

while (op){
u = q[op--];
--inD[v];
if (!inD[v])
q[++op] = v;
}
}

// Graph Initializing..

G.init(n);

REP_1(u, n) if (!inD[u]){

if (scr[u] > 0){
G.ae(G.s, u, scr[u]);
ans += scr[u];
}
else
G.ae(u, G.t, -scr[u]);

if (!inD[v]) G.ae(v, u, INF);
}
}

}
#undef v

int main(){

#ifndef ONLINE_JUDGE
freopen("/users/xiaodao/desktop/Exercise/in.txt", "r", stdin);
//freopen("/users/xiaodao/desktop/Exercise/out.txt", "w", stdout);
#endif

init();
printf("%d\n", ans - G.sap());
}